There is known a conventional method of absorbing the slack of a step chain of a passenger conveyor and giving tension to the step chain. In this method, a lower-part step chain wheel on which the step chain is wound is provided with an urging device that compresses a spring and tensions the step chain with any tensile force, the lower-part step chain wheel is moved by being pulled with the urging force of the spring when elongation has occurred in the step chain, whereby the slack of the step chain is absorbed and the step chain is tensioned with any tensile force (refer to Patent Document 1, for example).
There is also known a method that involves causing a controller to actuate a motor-driven hydraulic pump when the elongation of a step chain has been detected, pushing out a hydraulic cylinder directly connected to a lower-part step chain wheel by a hydraulic oil, whereby tension is applied to the step chain and the elongation of the step chain is absorbed (refer to Patent Document 2, for example).
[Patent Document 1]: Japanese Utility Model Laid-Open No. 54-133592
[Patent Document 2]: Japanese Patent Laid-Open No. 10-87252